1. Field of the Invention
The present invention relates to a brush for applying cosmetic products to hair. In particular the present invention relates to a brush for the application of mascara to eyelashes.
2. Description of the Prior Art
Brushes having a twisted wire core are known, such as, for example, mascara brushes used to apply mascara to a user""s eyelashes. A typical mascara brush is comprised of a core formed from a single metallic wire folded in a generally u-shaped configuration to provide a pair of parallel wire segments. Bristles (also referred to as filaments or fibers), usually comprised of strands of nylon, are disposed between a portion of a length of the wire segments. The wire segments are then twisted, or rotated, about each other to form a helical core (also known as a twisted wire core) which holds the filaments substantially at their midpoints so as to clamp them. In this way, a bristle portion or bristle head is formed with radially extending bristles secured in the twisted wire core in a helical or spiral manner. See, for example, U.S. Pat. No. 4,887,622 to Gueret, and U.S. Pat. No. 4,733,425 to Hartel et al.
The conventional purpose of a mascara brush is to apply mascara to a user""s eyelashes. To this end, brushes must be capable of picking up and transporting a supply of mascara from a reservoir and depositing it on a user""s eyelashes. See, for example, U.S. Pat. No. 4,365,642 to Costa, U.S. Pat. No. 4,733,425 to Hartel et al., and U.S. Pat. No. 4,887,622 to Gueret. Because of their greater flexibility and ability to bend around lashes to deposit mascara, softer, more supple bristles are thought to be better suited for applying mascara. Softer, more supple bristles are also thought to be less irritating to the user should contact occur. Bristles for a conventional twisted wire core mascara brush are generally made with a nylon material, e.g., polyamide, having a hardness or durometer substantially greater than 85D (e.g., approximately 115R on the Rockwell scale). To make the bristles of a conventional brush more supple, the diameter of the bristles is reduced to, for example, 2.4 mil (6 hundredths of a millimeter). However, the smaller surface area of smaller diameter bristles is thought to transfer less mascara than a larger diameter bristles. To compensate for the smaller surface area on each bristle, conventional brushes with smaller diameter bristles tend to have higher bristle density to increase the loading capacity. This yields a brush with a bristle envelope, also referred to herein as a brush surface (i.e., the relative envelope or surface defined by the bristle tips) that is xe2x80x9cclosedxe2x80x9d, i.e., that has few or narrow clearances or spaces between bristle tips.
Mascara, which is typically highly viscous, tends to clump when applied to eyelashes. The clumps of mascara are typically combed out as a finishing step to the application process. Stiffer bristles are thought to be better suited for combing out clumps and properly separating lashes. However, the combing and separating functions are thought to be better accomplished with brushes a having relatively open bristle envelope or brush surface, i.e., an envelope or surface that has numerous or wide clearances or spaces between bristles to make the brushes more xe2x80x98comb-likexe2x80x99.
Thus, a brush with softer, more numerous bristles was thought to be well suited for applying mascara but less well suited for combing out clumps and separating lashes. Conversely, a brush with stiffer, fewer bristles was thought to be well suited for combing and separating lashes but less well suited for applying mascara to lashes. While a separate brush can be used for each function, i.e., a soft brush for application and a stiff brush for combing, a single brush that can both apply mascara and comb out clumps would be preferred for the convenience of the user.
An example of a brush that is said to provide good application and combing characteristics is shown in U.S. Pat. No. 4,861,179 to Schrepf et al., which discloses a brush having a combination of conventional soft bristles and conventional stiff bristles. Another example of a brush said to provide good application and combing characteristics is shown in U.S. Pat. No. 5,238,011 to Gueret. The Gueret patent discloses bristles made of a soft material having a shore hardness of 20A to 40D (as noted above, a conventional bristle typically has a durometer of over 85D), and a large diameter in a range of 3.9 to 13.8 mil (10 to 35 hundredths of a millimeter), which is at least 1.5 mil (xcx9c4 hundredths of a millimeter) wider than a typical soft polyamide bristle). As disclosed by Gueret, the diameter is said to be sufficiently large to prevent too high a degree of suppleness. The resulting brush is said to have the same degree of suppleness or softness as a conventional softer brush. Accordingly, the bristles are equivalent in stiffness to conventional bristles.
While the forgoing brushes may be suitable for the application and combing of conventional mascara, currently preferred mascaras have significantly higher viscosity (two million CPS and above). Higher viscosity mascaras tend to collapse of bristles of conventional stiffness, thus rendering a brush having bristles of conventional stiffness ineffective for purposes of application or combing. Accordingly, the forgoing brushes would not be suitable for use with such higher viscosity mascaras.
Thus, there is a need for a brush that can transfer mascara (or another cosmetic) in sufficient quantity from a reservoir to an application point, apply the mascara uniformly and in desired amounts, and comb out any undesired excess while separating eyelashes.
A mascara brush is disclosed and claimed which has bristles that are both wider and stiffer than conventional xe2x80x9csoftxe2x80x9d bristles. To ensure that the brush is sufficiently supple to facilitate application of mascara and avoid irritating the user, the bristles are made from a material that is significantly softer than the material from which conventional bristles are made. The brush has a central core formed from a pair of twisted wire segments. A plurality of radially extending bristles is secured between the pair of twisted wire segments to form a brush portion at an end of the core. The bristles are secured in a quantity of from 4 to 27 bristles per turn of the twisted wire segments. Each of the bristles has a diameter of from 8 mil to 18 mil and is made from a thermoplastic elastomer material having a durometer of between 62D and 82D. Preferably, the bristles are made from an elastomeric polyester material having a durometer of about 72D, a diameter of 10 mil to 13 mil and are secured in a quantity of from 7-14 bristles per turn.
The wider, stiffer bristles made of a soft material surprisingly apply mascara uniformly and in desired amounts, and comb out excess while separating lashes. It is believed that the surprising and improved capabilities are due in part to the combined increase in stiffness and width of each bristle, which yields a more stable overall brush form and a wider individual bristle surface capable of better manipulating lashes to facilitate application and combing. In particular, the wider, stiffer bristles lift lashes better to facilitate application of mascara and to facilitate set the lashes such that they have a more pronounced curl. Additionally, the softer material of the bristles facilitates application of mascara.